Adaptive Secondary Frequency Regulation Strategy for Energy Storage Based on Dynamic Primary Frequency Regulation

Abstract

An innovative control strategy for adaptive secondary frequency regulation utilizing dynamic energy storage based on primary frequency response is proposed. This strategy is inactive when the system frequency remains within a predetermined frequency deviation threshold, whereby only the primary frequency regulation is executed through a combination of virtual droop and virtual inertia. The droop coefficient is dynamically related to both the state of charge (SOC) of the energy storage and the frequency deviation, adapting in response to these parameters. If the system frequency deviation exceeds, the integration link will be activated based on the energy storage participating in the primary frequency regulation of the power grid. This activation facilitates a segmented adaptive adjustment of the integral coefficient in accordance with the dynamic characteristics of system frequency variations observed during the regulation process. Additionally, the droop coefficient is incorporated as a modifying factor into the integral coefficient to enhance the control during secondary frequency regulation until all steady-state errors are mitigated. Disengagement from the secondary frequency regulation not only accelerates the restoration of grid frequency but also ensures precise and error-free adjustment of the system frequency, thereby improving tracking and dynamic performance. The effectiveness of the proposed control strategy is demonstrated through simulation.